Bench, mold and casting procedure, in particular for engine cylinders heads

ABSTRACT

This invention regards a bench, a shell and a casting procedure, particularly for engine cylinder heads, characterised by low-pressure casting, or the introduction of molten metal from a furnace into a shell positioned above it, exercising pressure on the surface of the molten metal inside the same furnace, combined with the free-fall feeding of the same shell. Free-fall casting takes place with open risers created in the shell, the latter being sealed at the top, at least in line with these risers, by lids moved by a tilting arm joined to the casting bench.

This invention generally regards aluminium casting technology and refersto the gravity mold casting and low pressure casting processes, whichuse specific molds and dies mounted onto casting benches andlow-pressure casting machines respectively for the two differenttechnologies.

Typical examples of these technologies are those used, not exclusively,to cast engine cylinders heads.

Generally, for medium and large-scale productions, all the aluminiumcastings of engine cylinders heads are produced with a gravitytechnology mold or a low-pressure technology die, as it is necessary touse inner cores to create the empty space inside the casting, and thiscannot be achieved using any other technology. The cores are sometimespartially used on the outside to obtain undercut figures which cannot beobtained with metal parts.

Aluminium castings for engine cylinders heads created in a gravity moldrequire casting benches on which to mount the molds. These benches areused to move the slides of the mold and the heads, and to expel thecasting from the mold using a plate fitted with ejectors, the techniquecurrently adopted by big foundries being to largely attribute theimportant technological functions to the mold itself. In the case ofengine cylinders head castings made using the low-pressure castingmethod, big foundries use the technique of attributing the majority oftechnological functions to the die for the same reasons as those adoptedwith the gravity casting technique.

In this case, besides moving the die, the low-pressure casting machineis also characterizied by using a modern system to carry out the castingprocess from the lower part of the die. As the lower part of the machineis occupied by the holding or maintenance furnace, the casting expulsionarea is always in the upper part. This expulsion is carried out using avertically sliding ejectors plate, which is rather hanged over as itexcludes the possibility of operating on the die axis directly fromvertically above, particularly affecting the core making device, whichcan only operate laterally, making it a very complicated device.

Generally Upper expulsion is never applied when the upper part of thecasting is obtained using sand cores, as the cast can only be liftedupwards if the upper part of the casting has been created using a steelmale where the casting can grip, as the cores crumble leaving thecasting in the mold. For this reason, in the case of gravity castingtechnology, when there are sand cores in the upper part of the casting,as almost always happens with this technology, expulsion is never fromthe top but always from the bottom.

At the moment, in all foundries, the molds or dies used are alwaysspecific, either for gravity casting or low-pressure casting, as the twotechnologies are completely incompatible. The casting benches ormachines for low-pressure casting are also completely different.

In the case of large-scale productions, instead of using a normal handladel for the casting of metal using the gravity casting technique, themolten metal is introduced into the mold from above using a ladeloperated by a casting robot, usually suspended from an overhanging beam,which is often also used for the automation of the core making deviceand the casting pick-up device.

The molten metal is taken by the robot from a nearby furnace and pouredthrough a basin into vertical and horizontal casting channel runners inthe mold until the figure and the open feeding risers are full.

The risers attract any slag in the molten metal, which floats into it,and are used to feed the casting as the cooled metal shrinks and torelease the gases contained in the molten metal, as well any furthergases which develop when the metal comes into contact with the cores,making the best possible casting in terms of mechanical characteristics,despite some collateral disadvantages.

In the gravity casting of engine heads, the molds and the castingbenches are usually placed on the ground, in pairs or multiples ofpairs, to facilitate the automation of the process. Alternatively, andonly in the case of gravity casting and not low-pressure casting, thewhole system can be mounted onto large, slow-moving turntables calledcarrousel conveyors so that the casting point is maintained stable asregards to the rotating movement. All the molds are filled by a singlerobot placed on a fixed station of the carrousel on which are fitted thebenches and the molds.

In the low-pressure process, the die comes into direct contact with thefurnace, as the furnace, situated under the machine, is raised in orderto make contact with the die. The lid of the furnace is equipped withone or more vertical pipes which are immersed in the “bath” of moltenmetal. The top of these pipes comes into direct contact with theinjection inlets applied to the drag of the die. With the low-pressureintroduction of dehydrated air between the surface of the molten metaland the lid of the furnace, the pressure of the air presses on the“bath” and forces the metal upwards into the mould through the immersedpipes and the injection inlets applied to the drag of the die until itis full. This die doesn't need any feeding risers as their function isperformed, by the pressure of the air exercised on the molten metal. Theupper part of the die is closed by a metal male which, besidesdetermining the casting figure, prevents the metal forced upwards by thelow pressure from coming out of the die. The air pressure is maintainedfor a short time, until the molten metal begins to solidify, facilitatedby coolers in the die and, in particular, on the injection inlets, whichcontribute to the rapid solidification of the metal in the upper part ofthe inlet hole, preventing the molten metal injected into the die fromreturning, due to the force of gravity, into the furnace when the airpressure is released and allowing the molten metal contained in thecasting pipes to return into the “bath”, avoiding its solidification.The solidified metal in the upper part of the injection inlet is thenexpelled together with the casting.

From that described above it is possible to easily deduce that, at thestate of the art, to obtain a casting, it is first necessary to decidewhether to use the gravity casting or low-pressure technique, as the twotechnologies are very different. In addition to the mold or the die, thecasting bench or low-pressure casting machine must be suited to thechoice of gravity or low-pressure casting. Once the decision has beenmade, the mold or die must be made in according to this final decision.The design and construction phases of this operation are very expensive,so a definite decision must be made before going ahead.

The decision to opt for one technique or the other is not alwayssatisfactory, especially with regard to the low-pressure castingtechnique, as the decision, unless made in accordance with a specificrequest by the customer, is made on the basis of the founder'sexperience or depending on the equipment available at the foundry.

All existing casting technologies have their pros and cons. For example,an advantage of low-pressure casting is that the molten metal istransferred through immersed pipes to the bottom of the holding furnace,avoiding the inclusion in the metal of slag and smelting residues thatfloat at the top of the “bath”. As the whole casting process takes placein a closed system and has no contact with the outside atmosphere,surface oxidisation is avoided. Should this occur, it would remain onthe surface of the bath and would never enter the die, unlike that whichoccurs with gravity casting. This technology involves taking the metalfrom a furnace near the mold and, despite all the precautions taken,small amounts of floating slag could also be introduced into the mold.The majority of this slag collects in the risers without causingexcessive damage to the casting. It is harder to avoid taking surfaceoxidisation from the furnace, which is added to oxidisation created inthe ladel and during the casting process itself, as everything takesplace in contact with the outside atmosphere. Another negative aspect ofgravity casting is the turbulence which is generated in the metal duringthe casting process, which can cause slight damage to the casting.

The negative aspects that characterise gravity casting in terms ofquality are not serious, and are less important than those thatcharacterise low-pressure casting which, due to the very fact that it isnot possible to discharge any sullage into feeding risers, which are notpresent in this technology, along with the gases contained in the metaland those generated when this metal come into contact with the cores,together with other factors, cause a very high number of rejects due toporosity in the castings. In order to limit the consequent economicdamage, many foundries have applied an automated full sodium silicateimpregnation process to 100% of the production obtained with thelow-pressure casting technology.

The fact that, despite the various negative factors, everything possibleis done to use the low-pressure technique, depends largely on the factthat it allows considerable savings on manufacturing costs. This is dueto the fact that less metal is required for each individual casting, asthe feeding risers and vertical casting channels are eliminated.Consequently, the mechanical processes needed to separate the risersfrom the casting are also eliminated, as are the costs involved inrecasting these and the vertical channels.

As mentioned earlier, as regards gravity casting molds and low-pressuredies, these are made as completely as possible, from a technologicalpoint of view, by the leading manufacturers of cylinders head castings.It is worth noting that the casting benches and low-pressure castingmachines are always in operation and are part of the foundry's fixedmachinery assets. As such they are available in strictly limited supply,while molds and dies are supplied in the quantities required forproduction and for the various different cylinders heads required, withconsequent high costs for every mold or die produced.

That described above highlights the need for strictness when opting forgravity casting or low-pressure casting technology, without leaving roomfor the chance to intervene if the technology used is found to beunacceptable, but all this can be avoided by that indicated in the aimsand advantages of the invention.

The main aim of this invention is to add a new type of castingtechnology to those that already exist. The new technology will be knownas “combined” technology and will be capable of fully exploiting theadvantages that obtainable by gravity and low-pressure castingtechnologies.

Another aim of the invention is to present a new casting bench capableof holding both molds and dies and of enabling the easy passage from onecasting technique to the other. For this reason, the tool thatdetermines the outer figure of the casting, currently called mold or diedepending on the technology used, will be referred to herein exclusivelyas mold.

Another aim of the invention is that of enabling the operator tothoroughly clean the mold after extracting the casting and, wherenecessary, to quickly repaint the parts of the figure of the mold on thebench, with a very short production interval, which, being hot,facilitate the solidification of the paint, without preheating the moldoff the production line and so extending the production time.

Another aim of the invention is to present a single standardised castingbench which always enables the expulsion of the casting from the bottomof the mold, even when, in the case of low-pressure casting or“combined” technology, the holding or maintenance furnace is placedunder the mold. This eliminates all cases of expulsion of the castingfrom the top of the mold, even when the latter is equipped with a metalcope or an upper male, freeing the vertical space above for morerational use by the core assembling robot and the casting extractionrobot, without the need for complicated devices with a doublevertical/horizontal movement.

Another aim of the invention is to present a support which can beapplied to the top of all the molds, for all casting technologies,equipped with a vacuum chamber for connection to a vacuum system toremove fumes and gases from the mold during casting.

Another aim of the invention is to transfer some of the parts of themold which do not form the casting figure, known as frames, from themold to the casting bench, so that they are built just once with thebench and, being standardised, are not copied to provide the number ofmolds needed for production and for the various kinds of castings andcasting technologies.

Another aim of the invention is to present a casting bench equipped witha lower structure the height of which may be adapted to suit the castingprocess used. In particular, in the case of gravity casting, where thereis no furnace underneath the mold, the bench may be lowered for mountingon carrousels. The same standard bench for use on carrousels may also beplaced directly on the ground when using the traditional gravity castingsystem, but with smaller, lighter and cheaper molds.

Another aim of the invention is to enable the transformation of a moldfor gravity casting technology for use in low-pressure technology,constructing a metal upper male and related accessories, which willreplace the core which usually forms the risers and the upper figure;consequently the mold will have no risers. It will be easy to revert togravity casting using “combined” technology, setting aside the uppermale and using the core again.

Yet another aim of the invention is to provide a casting bench withsplit, overlapping slides carriers for core making reasons, on bothslides carriers (right/left) or on just one side. The opening andclosing movement of the two halves of the slides carriers will takeplace independently by way of hydraulic cylinders or simultaneously(parallel movement), when split movement is not required. If there areno core making problems, the slides carriers will be supplied in asingle unit.

A consequence of the invention is the elimination of the casting robotfor gravity casting molds, placed on the ground, when these aretransformed for low-pressure casting or “combined” technology. The entryof the metal into the mold will take place from the underlying furnaceand consequently the movement of the casting robot on the beam, usuallypositioned above the mold, will also be eliminated where the beam isalready occupied by the core making device to place the cores in themold and the casting pick-up device, facilitating the movement of thelatter.

This invention presents a standardised conformation of the toolings usedfor the production of a casting for engine cylinders heads or othercompatible castings, with a single standard casting bench for the newmolds presented here, or those which already exist and are modified forthis purpose, for all the casting technologies referred to above, withinferior expulsion of the casting and with a tilting arm for moving allthe parts of the mold situated in the upper part. The molds for thefollowing technologies will be mounted on the standard bench:

-   -   molds for low-pressure casting technology with metal upper male;    -   molds for “combined” technology, or with low-pressure casting        and gravity feeding through risers created in the upper core;    -   molds for “combined” technology with low-pressure casting and        gravity feeding through risers created in the metal cope;    -   molds for traditional gravity casting technology with upper        casting basin and gravity feeding through risers created in the        upper core;    -   molds for traditional gravity casting technology with upper        casting basin and gravity feeding through risers created in the        metal cope.

The casting procedure according to this invention envisages theconcentration of all the toolings in the same production space, with theuse of a single casting bench for all casting technologies and with thesame holding furnace, both for molds with low-pressure casting and moldswith low-pressure casting but with gravity feeding through risers, bymeans of use of the new casting technology, known as “combined”technology.

To simplify the molds, making them standard for all technologies, and toreduce their weight and cost, a consistent part of the frames has beentransferred from the mold to the bench, as specified further on.

Substantially, the mold is formed as follows: drag, slides, fixed headsapplied to the drag, mobile heads, where fitted, which slide in thefixed heads, lower ejectors plate and, depending on the technology used,male, cope or simply a vacuum upper lid plate. The male and cope willalso be mounted on a vacuum plate which will then be mounted on asupport. The casting bench will be given slides carriers, the baseplate, all the guides and sliding gibs. Consequently, the molds will becheaper to make, will weigh much less and will be smaller, enablingsavings during transportation over long distances, within the factoryand during storage.

The casting bench and the mold will be managed by the same computer thatcurrently manages the furnace and the low-pressure casting technologymachine, so the bench will replace the machine, becoming standard forall technologies. The bench will be strong, properly cooled andinsulated, so that it is not affected by thermal dilation. The mold willbe free to dilate as necessary and to reach the right thermal balancewith the addition of coolers governed by the computer. The operationsfor clamping the drag, hooking the slides on the casting bench andfastening the ejectors plate will take place quickly by way of hydrauliccylinders (jacks).

The mobile heads, where fitted, will be moved by hydraulic cylinders andwill be hooked up manually but quickly by way of a shot sleeve whichblocks the mushroom of the head with that of the hydraulic cylinder.

With the same bench it will therefore be possible to obtain castingswith gravity feeding but feeding of the molten metal from below, as inthe case of low-pressure casting. This process will be called “combined”technology. In this case, to prevent the molten metal from overflowingthrough the risers, the mold will be fitted with a support with theplate covering the entire riser area to contain the thrust of the metal.This plate will also act as a vacuum plate, being mounted on the supportwith vacuum chamber. This support is applied and moved by a tilting armhinged to the top of the bench.

The support will be connected to a vacuum device which will suck fumesand gases produced by the molten metal and from contact with the coresthrough the plate. For this purpose, the vacuum plate with the metalmale or cope will be equipped with filters in line with the upper corerisers or the figure risers to allow the evacuation of fumes and gases,blocking the passage of the molten metal. Therefore, the support andeverything applied to it are an integrated part of the mold. Inparticular:

-   -   support with vacuum plate, which did not previously exist and is        therefore part of the new design, for use in the new “combined”        technology (low-pressure casting    -   gravity feeding through risers), both to vacuum fumes and gases,        and to seal the upper surface of the mold and the cores that        generate the feeding risers, to contrast and block the thrust of        the metal of the casting feeding risers, preventing the molten        metal from overflowing during the casting phase;    -   support as above with vacuum plate and fitted metal cope used in        the new “combined” technology to seal the upper surface of the        mold in line with the risers. The aforementioned cope acts as        the male which generates the upper figure of the casting and,        together with the slides, the risers that feed the casting using        the gravity technology;    -   support and vacuum plate to which a metal male is applied, used        in low-pressure casting technology to generate the upper figure        of the casting without the risers.

The support with vacuum plate, the support with vacuum plate and copeand also the support with vacuum plate and upper male, applied to thethree technologies, are all made with a plate to which filters areapplied in line with the risers and the figure. These filters convergein a fume and gas vacuum chamber, created in the support, which will beconnected to a vacuum device. This vacuum is destined to improve thequality of the castings with all the technologies, includinglow-pressure casting technology, inasmuch as, with appropriate vent sloton the sides of the male and internal passages, it is possible to getclose to the cores to vacuum fumes and gases, the majority of whichcurrently remain inside the cast, generating widespread porosity.

The introduction of the new fume and gas vacuum system to all thetechnologies, including low-pressure casting, will contribute toimproving the quality of castings and the working environment,regardless of the technology used.

The new mold used in the “combined” technology process will have nocasting basin and no vertical casting channels, although the new projectof mold provides for their presence without moving on to the final phaseof construction. The casting will be extracted using a standard deviceinserted into the base plate of the bench and made up of a plate holderonto which the ejectors plate with which all molds are equipped will bequickly fastened using hydraulic cylinders (jacks). In order torecuperate existing molds, the vertical casting channels in the lowerpart will be plugged.

Both new and existing molds will be fitted with injection inlets in thedrag, envisaging a fast cooling technique like that used in low-pressuretechnology to solidify the molten metal and avoid the return of theliquid metal into the furnace due to the force of gravity when the airpressure is cut off.

This new casting technique eliminates the disadvantages of gravitycasting deriving from taking slag from the furnace and oxidisation,maintaining advantages such as discharging the same slag and gases andfumes that develop during the casting process through the risers, whichare now sucked out by the new devices illustrated and claimed.

With the application of the metal male envisaged in molds forlow-pressure casting, which is replaced by a core or a metal cope in thegravity casting procedure, all of which are managed by the same tiltingarm on the bench, it is possible to easily transform a gravity castingmold into a low-pressure casting mold by adding injection inlets in thedrag (lower part of the mold), and from lower-pressure to gravity byremoving the male and replacing it with a core.

The automation of a gravity casting line of the current type envisagesthe use of a core making device a casting robot and a device for pickingup the casting. All movement often takes place on the same beam andthree devices are hard to manage. With the elimination of the castingrobot, the coordination of the movements is simplified, inasmuch asthree are reduced to two, saving time and money. The furnace next to themold is also eliminated, recovering production space.

The newly designed bench, to which various functions have beenattributed, particularly the suitability for holding low-pressurecasting molds and molds for free-fall casting, as well as those for usewith “combined” technology, is also used for housing a part consistingof components that are normally part of the frames of the same molds.Consequently, these components will be made just once and will be anintegrated part of the bench, thus avoiding the need to make new onesfor every mold and for all the variants required for the various typesof cylinders head castings or for other castings. In this way, the moldswill cost and weigh less and be smaller.

From that described above, it should be obvious that the foundry will nolonger have the problems described in the state of the art when choosingthe casting technique best suited to the casting to be made, as it iseasier to make changes if the choice made should turn out to be wrong,passing from one casting technology to the another by making slightalterations to the molds.

With the adoption of the newly designed benches, as with the newlydesigned molds, it is possible to make considerable savings oninvestments and save production space, and with the use of the combinedlow-pressure/gravity feeding technology it is possible to obtaincastings with impressive mechanical characteristics, reduction ofrejects and improved production in terms of quality and quantity. Themold can be used for longer by simply repainting the figure parts.

As well as having a bench arm which can be tilted by over 90°, theslides carriers of the mold slides can rotate upwards by over 45°,allowing the operator to easily repaint the mold figure and to clean it.

As mentioned earlier, the new bench, excluding the lower part of thestructure, can be used on a carrousel or on the ground when it isnecessary to use the traditional gravity casting technology, as happensnow. The frames of existing molds can easily be altered to standardisethem and for use on the new bench. New molds will be made in accordancewith the new project but will still have the traditional basin andvertical casting channels as traditional

BRIEF DESCRIPTION OF THE DRAWINGS

Further details and characteristics of the invention will become moreobvious as some examples of versions of benches and molds are describedand illustrated in the enclosed drawings, which are purely indicativeand in no way binding, and in which:

FIG. 1 shows a vertical section of a bench for single-slides mold withthe tilting arm raised and with a holding or maintenance furnace;

FIG. 1 a shows a partial section of an enlarged part of the bench shownin FIG. 1;

FIG. 2 shows the top view of the bench;

FIG. 3 shows a vertical section of the bench seen from the side;

FIG. 3 a shows a partial section of an enlarged part of the FIG. 3;

FIG. 4 shows the bench seen from below;

FIG. 5 shows a prospective view of the bench in the working position,with the tilting arm lowered, but without the mold;

FIG. 6 shows a vertical section of a bench seen from the front with theslides carriers inclined for cleaning and repainting of the mold figureparts;

FIG. 7 shows a vertical section of a bench similar to that shown in theprevious Figures, but for a mold with overlapping double half slides;

FIG. 8 shows a section of the bench shown in FIG. 7 seen from the sideand with the double half slides inclined;

FIG. 9 shows a prospective view of a casting bench similar to that shownin FIGS. 1-6, but with the supporting frame lowered for gravity casting,in the working position but without the mold;

FIG. 10 shows a top view of a mold for “combined” technology with theslides open, for low-pressure casting but fed through gravity riserscreated in the upper core;

FIG. 11 shows a cross-section of the open mold shown in FIG. 10;

FIG. 12 shows a longitudinal section of the closed mold;

FIG. 13 shows a prospective view of the closed mold;

FIG. 14 shows a cross-section of an open mold for “combined” technologywith double slides and metal cope;

FIG. 15 shows a longitudinal section of the closed mold shown in FIG.14;

FIG. 16 shows a prospective view of the same mold;

FIG. 17 shows a cross-section of an open mold with a metal upper maleexclusively for low-pressure casting technology;

FIG. 18 shows a longitudinal section of the mold shown in FIG. 17closed;

FIG. 19 shows a top view of an existing mold for gravity casting,altered for adaptation to the bench described in the invention, with thesides open;

FIG. 20 shows a cross-section of the open mold shown in FIG. 19;

FIG. 21 shows a longitudinal section of the same mold closed; and

FIG. 22 shows a prospective view of the same mold closed.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, FIGS. 1-6 show a bench suitable for thequick loading of single-slide mold and for a low-pressure castingprocess or for a new technology, called “combined”, which envisages alow-pressure casting process fed using the gravity technique throughrisers created in at least one core or in the cope of the mold.

In order to better understand the structure of the new bench presentedhere, the main elements of a mold suitable to be loaded on this benchare described below. Further details of the mold and its alternativeversions will be described. With reference to FIGS. 10-18, a moldcomprises at least one drag 35, an ejectors plate 38 fixed under thedrag, two slides 40, 40′, front 42 and rear 42′ fixed heads applied tothe drag 35, front 44 and rear 44′ mobile heads, where fitted, whichslide in the fixed heads. Inlets 36 for coupling to pipes protrudingfrom a furnace containing molten metal and channels 36′ for deliveringthe metal into the mold are created in the drag 35.

Returning to FIGS. 1-6, the casting bench mainly comprises a lower mainstructure 30, suitable for housing a holding or maintenance furnace 32,an upper main structure 31 resting on the lower structure, a base plate29 resting on the upper main structure 31, a cooled plate 16 positionedon the base plate 29 and on which the drag 35 of the mold will rest, aplate holder 17 underneath the cooled plate 16 to which the moldejectors plate 38 will be hooked up, and two slides carriers 1 supportedby rotating supports 2. The cooled plate 16 has a central opening 16′into which the mold ejectors plate 38 is fitted to hook onto the plateholder 17.

The furnace 32 is fed by molten metal from another melting furnace andis equipped with two pipes 32′ for the injection of the metal into themolds using the low-pressure and “combined” technologies.

At the top of the bench there is a hinged tilting arm 8 carrying acylinder 10, for vertical movement to and from the edge of the mold, towhich the top of the mold is hooked, as will be described further on inthis document.

For quick hooking of the mold ejectors plate 38 to the bench's plateholder 17, the latter is equipped with a slide 19, moved by a cylinder21, destined to hook on to mushrooms 39 protruding from the ejectorsplate 38. Similarly, the slides carriers 1 are equipped with slides 24,moved by related cylinders 25, destined to hook on to mushrooms 41′ onthe slides 40, 40′ of the mold for quick fastening to the slidescarriers 1. The latter are activating by cylinders 4 and run alongcolumns 5 and sliding gibs 20.

FIG. 2 shows four cylinders 18, which, working in traction, move theplate holder 17 to which the casting ejectors plate 38 is fixed, andfour more cylinders 15 for the quick clamping of the drag 35 of the moldto the cooled plate 16.

FIGS. 3 and 3 a show cylinders 11 for moving the tilting arm 8 andreference keys 23 fitted to the slides carriers 1 for centring theslides 40, 40′ of the mold.

In FIG. 4 it is possible to see the lower casting expulsion devicecomprising the bench's plate holder 17, which is suitable for acceptingall types of ejectors plates 38 for all the casting technologies, whichare part of the mold.

FIG. 5 shows the slides carriers 1 controlled by cylinders 4, slidingalong the guide column 5 and sliding gibs 20 (FIG. 1 a), the rotatingsupports 2 for the slides carriers 1, with related pivots 2′, the arm 8and related pivots 28. In the front part of the bench there is a supportfor locking the arm 8 using a hydraulic cylinder 28′ (jack) during themetal casting phase and while extracting the cope or the upper male fromthe casting or while simply raising the vacuum and clamping platesupport of the mold.

FIG. 6 shows the slides carriers 1 inclined for cleaning and repaintingthe mold figure parts, the related oscillating cylinders 7 fixed to theupper structure of the bench, and the joint between the upper 30 andlower 31 structures.

FIGS. 7 and 8 show a casting bench for use with low-pressure and“combined” technologies, like that described in the previous Figures,but suitable for accepting overlapping double half-slides molds, whichare sometimes indispensable during the core making phase. Depending onrequirements, these can also operate simultaneously, connecting them ina parallel position so that they become a single slide. The half slidesside can also be applied on just one side. The bench is fitted withlower 33 and upper 34 half slides carriers which slide along guide gibs20 and columns 5. It is possible to see the double cylinders 4 formoving the half slides.

The bench shown in FIG. 9 differs from those illustrated previously inthat it is a low-level structure, the lower part 30 of the samestructure having been removed. The bench is only suitable for gravitycasting and can be mounted on a carrousel or positioned on the ground.

FIGS. 10-13 show a mold for the new “combined” technology forlow-pressure casting fed using the gravity technique through riserscreated in an upper core (not shown). There are inlets 36 and channels36′ for delivering the metal into the mold, skirtings 43 for quicklyclamping the drag 35 to the base of the bench, mushrooms 41′ for quicklylocking the slides 40, 40′ to the slides carriers 1 of the bench. Themold also includes a support 46 for connection to the cylinder 10carried by the tilting arm and to which a fume and gas vacuum plate 45is fastened. The support 46 also contains a communicating vacuum chamber46″ with a vacuum outlet 48. Number 44″ is used to indicate the emptyspace that will be occupied by the cores after core making.

FIG. 13 shows seats 46′ for a pivot 28″ for hooking on the tilting arm 8of the bench (FIG. 1), the keys seats 23′ for centring the slides 40,40′ in the slides carriers 1, and keys seats 14′ for centring the drag35 on the base plate of the bench.

FIGS. 14-16 show a double-slides mold, suitable for the new “combined”technology consisting in pouring the metal at low pressure and feedingthe casting using the gravity technique through risers 51′ created in ametal cope 51 fastened to the support 46 with a vacuum plate 45′. Themold is equipped with lower half slides 49, 50 which enable core makingwhich would otherwise be impossible, and upper half slides 49′, 50′which complete the composition. This mold can be mounted and movedexclusively from the double-overlapping slides bench shown in FIGS. 7and 8.

In the case of low-pressure casting, the metal cope 51, to create thefigure of the upper part of the casting, is replaced with a metal male52, as shown in FIGS. 17 and 18. This too is fastened to a vacuum plate45″ and is equipped with vacuum holes or channels 52′ at the bottom ofwhich there is a filter to block the passage of molten metal.

FIGS. 19-22 show an example of an existing mold for gravity castingwhich can be adapted for use with the new bench. The change consists inremoving part of the frames from the mold, indicated with dotted lines,to standardise it in compliance with the new project, as these parts arealready present on the new bench. By adding the casting inlets 36 on thedrag 35 for delivering the metal at low-pressure and retaining thecasting feeding risers, it is also possible to use the “combined”technology for existing molds. In particular, the parts eliminated arethe base 55 with the related accessories and the supports 56 for theslides 57. To standardise the latter one it is possible to add plates58. The casting basin 53 can be retained, even if not used, by closingthe related casting channels 54 and 54′.

In short, the innovative characteristics of the casting bench presentedhere are:

-   -   single standard bench for molds with traditional gravity casting        technology and for molds with low-pressure casting technology,        the only variant being the structuure's type as low-level        structure for gravity casting inasmuch as, for this technology,        which does not provide for the use of the holding furnace, the        lower part of its structure is removed;    -   single standard bench, for casting from the lower part (drag)        for “combined” technology, for low-pressure casting molds with        gravity feeding of the casting through risers (use tall        structure);    -   single standard bench from which upper expulsion has been        eliminated in the case of all technologies, transferring this to        the lower part using a new expulsion device inserted into the        base plate. At the moment, upper expulsion is applied to all        machines for low-pressure casting technologies. The elimination        of upper expulsion makes core making and extraction of the        casting easier by facilitating automation;    -   single standard bench with expulsion of the casting obtained        from below in the case of all casting technologies, including        low-pressure casting, through a new device inserted in the base        plate, even if it exists in the lower part of the holding        furnace;    -   single standard bench, with tilting arm to which a support with        a cope support plate or a upper male support plate or even just        a plate for sealing the risers is applied, all of which are part        of the mold. All the supports, plates, copes and upper males are        made specially to allow the vacuuming of fumes and gases. The        tilting arm is also suitable for molds with two identical        figures, and therefore with two feeding head copes or two males        or an enlarged sealing plate made to allow the vacuuming of        fumes and gases from the casting;    -   single standard bench with part of the frames normally        attributed to the molds built-in to it, and therefore requiring        construction just once. Valid for all technologies with savings        on weight and construction cost on molds    -   single standard bench for all casting technologies with slides        carriers that tilt upwards by about 45° to clean the slides of        the mold and repaint areas of the figure;    -   single standard bench to which it is possible to fit split,        overlapping slides carriers instead of single versions, onto        which the half slides of the mold can be mounted quickly using a        slide controlled by a cylinder fitted to each individual half        side. Either one or both sides can be split. The slides carriers        can also operate parallel with one another and revert to        operation as a single slide    -   single standard bench for mounting on a carrousel, the only        variant being the use of the low-level structure, as, for        various operating reasons, only molds with traditional gravity        casting technology which do not necessitate the underlying        furnace can be used on carrousels;    -   single standard bench like that described in the previous        paragraph for use on the ground, when it is necessary to use        traditional gravity casting technology with a casting robot, but        with the newly designed mold or an existing mold with altered        frames.

The innovations regarding the mold can be summarised as follows:

-   -   molds for gravity technology but with injection of the metal        from below using the low-pressure casting technology, retaining        the best aspects of gravity casting technology with casting        feeding risers, adopting the “combined” technology. These molds        have no casting basin and no vertical casting channels, but are        fitted with injection inlets in the drag, like those used in        low-pressure casting technology;    -   molds like those described in the previous paragraph, for        “combined” technology, to which a plate has been applied in the        upper part, fastened to a support equipped with a vacuum chamber        and an outlet for connection to a vacuum device for vacuuming        fumes and gases. The support is moved by the tilting arm on the        bench. The plate applied to the support is equipped with filters        that converge in the support chamber and covers the whole area        of the risers and the upper core to prevent the metal from        overflowing. The plate is pressed onto the upper surface of the        mold by the vertical hydraulic cylinder on the arm;    -   molds like those described in the previous paragraphs, where the        upper figure is obtained using a metal cope with casting feeding        risers. The cope is applied, for vacuuming fumes and gases, to a        plate which also seals the top of the risers;    -   molds for low-pressure casting technology, where the upper part        is obtained using a metal male which will be fastened to a plate        equipped with filters and vents for vacuuming fumes and gases.        The plate will vacuum gases and fumes from vertical vents slots        created on the sides of the male and from through holes in the        same male, using a vacuum device attached to the support        equipped with a vacuum chamber.    -   newly designed and constructed molds for all casting        technologies, from which part of the frames have been removed,        attributing them to the bench, obtaining smaller molds which        weigh and cost considerably less.    -   existing molds for the current gravity and low-pressure casting        technologies, to be changed to eliminate parts of the frames        already attributed to the new bench and with the construction of        a few accessories to standardise them in compliance with newly        constructed molds, for use in gravity, low-pressure and        “combined” technologies;    -   existing or new molds for all casting technologies, where the        expulsion of the casting takes place from below using a new        expulsion device fitted to the bench, onto which the mold        ejectors plate is fastened.    -   existing or new molds all equipped with “mushrooms” for mounting        and quickly locking the ejectors plates, slides or half slides        onto the new bench;    -   existing or new molds for gravity casting, with reduced frames        and weights, for mounting on new benches positioned on        carrousels or on the ground.        Description of an Operating Cycle for Assembling a Shell on the        Bench

1) Place the complete mold on the base plate 29 of the bench,positioning the drag 35 in the centring keys 14.

2) Clamp the drag to the base plate with quick fastening by means of thefour hydraulic cylinders 15.

3) Hook the mushroom 39 of the lower ejectors plate to the plate holder17 using the slide 19 and the hydraulic cylinder 21.

4) Close the slides carriers 1 of the bench equipped with centring keys23 on the mold slides and hook the slides (mold figure inserts) usingthe two slides 24 controlled by hydraulic cylinders 25.

5) Hook the mobile heads 44 and 44′ of the mold manually to the relatedhydraulic cylinders using the shot sleeves supplied with the bench.

6) Close the tilting arm 8 of the bench and lock it in place with thehydraulic cylinder 28′. Hook the cope or male or the plate to the moldsupport 46 for fume and gas vacuuming, lowering the cylinder 10 andusing the hooking pin 28″ of the bench to hook up the mold support 46.

7) Connect any mobile males on the mold to the automatic system governedby the computer.

8) Connect the Venturi pipes, where present and if required for use.

9) Connect the coolers.

10) Connect the vacuum device to the mold vacuum chamber support inlet,supported and moved by the arm of on the bench for vacuuming fumes andgases.

11) Test all the manual cycle movements, including the movement of thetilting arm and the ejectors plate holder.

12) Run empty automatic cycles after connecting the computer andselecting the programme to suit the casting technology to be used.Return to the manual cycle.

13) Heat the mold if it has not already been preheated off theproduction line, ready for painting.

14) Use the manual control to open and tilt the slides, rotating the armto the open position.

15) Paint the mold FIG. 1 f this has not already been done off theproduction line: drag, slides, any heads, any cope or upper male.

16) Clean thoroughly, place the slides in the vertical position, carryout manual cycle test of all movements after heating and painting. Placeeverything in the open position with the ejectors plates in the lowposition.

17) Place all the cores in the mold (core making) and clean it.

18) Close the mobile heads, slides, any males on the mold, tilting arm,lowering hydraulic cylinder on the arm with support and anything elseapplied, to lock the top of the mold.

19) Lift the holding or maintenance furnace into contact with the moltenmetal inlets used in low-pressure casting or “combined” technology.

20) Check the temperature of the mold and the molten metal in thefurnace.

21) Switch on the automatic production cycle.

When using molds with four half slides or just two half slides on oneside and a single slide on the opposite side, remember that, for coremaking purposes, only the lower half slides must be closed at the startof the cycle. The automatic cycle must be suited to requirements.

Description of an Automatic Production Cycle for a Bench and a Mold withTwo Slides

1) Start cycle with:

-   -   a-slides open in the vertical position    -   b-mobile heads open    -   c-ejectors plate in the low position    -   d-tilting arm open and all supported parts in the raised        position        2) Automatic core-making with core making device.        3) Cleaning with a blast of air during the cycle to eliminate        any grains of sand which become detached during core-making.        4) Closure in sequence of heads, slides and any mobile males on        the mold.        5) Rotation of the arm in the operating position with the upper        male or cope or closing and for fume and gas vacuum plate        attached, depending on the casting technology.        6) Lowering by the hydraulic cylinder of the arm of the cope or        the upper male or the closing and for fume and gas vacuum plate;        placing that applied to the arm in the operating position.        7) opening of the fume and gas vacuum system. Opening of the        Venturi pipes, where fitted and if necessary.        8) Casting depending on the mold mounted and according to the        specific program, for the specific casting technology chosen.        9) opening of timed coolers.        10) Timing of solidification.        11) Closing of timed coolers.        12) Raising of the cope or upper male to remove them from the        casting, or of the sealing and fume and gas vacuum plate, if the        upper part is created using a core.        13) Rotation of the upper arm to the open position.        14) Opening (extraction) of any mobile males on the mold.        15) Opening and rotation of the slides upwards by about 45°.        16) Opening of the mobile heads.        17) Expulsion of the casting out of the drag by the plate holder        with the ejectors plate.        18) Positioning of casting pick up pliers.        19) Hook up of casting.        20) Removal of the casting from the mold.        21) Lowering of the plate holder with ejectors plate.        22) Cycle cleaning with mold open using air.        23) Start new production cycle. 3

1-27. (canceled)
 28. A casting procedure, particularly for enginecylinder heads, comprising steps of: providing for a mold having openfeeding risers for feeding the casting as the cooled metal shrinks andfor attracting any slag, fumes and gases contained in the molten metal;forcing molten metal to flow into the mold from a furnace situated belowsaid mold by exerting a pressure on the surface of said molten metal;and sealing the top of the mold, at least at the level of the openrisers, using a plate which prevent the molten metal introduced underpressure from overflowing and which is connected to a vacuum device forvacuuming fumes and gases.
 29. A casting procedure in accordance withclaim 28, in which the expulsion of the casting from the mold takesplace below it.
 30. A casting procedure in accordance claim 29, in whichat least the upper part of the figure of the casting is obtained usingcores.
 31. A casting procedure in accordance with claim 29, in which atleast the upper part of the figure of the casting is obtained using ametal cope.
 32. A casting machine for receiving a mold, where the moldis equipped with a bottom and an ejector plate extending downwards fromsaid bottom, the casting machine comprising a lower main structure (30)suitable for housing a holding or maintenance furnace (32) for feedingthe mold in a low-pressure casting procedure or in a casting procedureaccording to claim 28, an upper main structure (31) resting on saidlower structure, a base plate (29) resting on the upper main structure(31), a cooled plate (16) positioned on the base plate (19) and suitablefor receiving the bottom (35) of the mold, and further comprising,underneath the cooled plate (16), a plate holder (17) to be fastened tothe ejectors plate of the mold and running vertically between aninactive lowered position and a raised casting expulsion position.
 33. Acasting machine according to claim 32, wherein the cooled plate (16) isfitted with an opening (16′) for passage of the ejectors plate (38). 34.A casting machine according to claim 33, comprising quick lock means forfastening together the ejectors plate (38) of the mold and the plateholder (17) of the casting machine.
 35. A casting machine according toclaim 34, in which the mold ejectors plate has a pair of mushrooms (39)and in which the plate holder of the machine is provided with a slide(19) which runs along the plate holder and has slots adapted to receivethe mushrooms and to lock them in place following the movement of theslide controlled by a hydraulic cylinder (21).
 36. A casting machineaccording to claim 32, especially for engine cylinders heads, destinedto receive a mold with two sides, comprising two sides carriers (1)which are fixed to the corresponding side of the mold and slide alongguide columns (5) and sliding gibs (20) fitted to the machine for amovement of the slides by hydraulic cylinders (4).
 37. A casting machineaccording to claim 36, in which the sides are fastened to the sidescarriers by automatic quick locking devices.
 38. A casting machineaccording to claim 37, in which every sides carriers has a slide (24)with slots to receive a pair of mushrooms which protrude from the sideof the mold and lock them in place following the movement of the slidecontrolled by a hydraulic cylinder (25).
 39. A casting machine accordingto claim 38, in which the sides carriers (1) are hinged to the sides ofthe machine, making it possible to rotate then upwards by means ofoscillating hydraulic cylinders (7) fitted to the machine to enable easycleaning and repainting of the figure parts of the sides of the molds.40. A casting machine according to claim 36, in which at least one sideof the mold is made in at least two overlapping parts and in which therelated side carrier is made up of at least two corresponding parts,each of which is moved by a hydraulic cylinder (4), said hydrauliccylinder being controllable independently or in parallel.
 41. A castingmachine, especially for engine cylinder heads, with a tilting arm (8)hinged to the top, destined for the movement of a metal male forlow-pressure casting or a casting according to claim 28, and/or for themovement of sealing means for the upper part of a mold positioned on themachine, depending on the casting process used.
 42. A casting machineaccording to claim 41, in which the metal male and/or the sealing meansof the upper part of the mold are attached to a hydraulic cylinder (10)carried by the tilting arm for their vertical movement.
 43. A castingmachine according to claim 41, in which, during the casting process, thetilting arm is closed on the bench and locked to the latter from theopposite side compared with the hinged side by a locking device, such asa jack (28′).
 44. A casting machine according to claim 32, wherein themain lower structure (30) is removable from the upper structure (31) forplacing said upper structure on a carrousel or on the ground for agravity casting procedure.
 45. A mold for obtaining castings, especiallyengine cylinders heads, comprising a bottom (35) and an upper partobtained through cores or a metal male, characterized by the fact thatsaid bottom is provided with inlets (36) for coupling to pipes from afurnace placed underneath the mold and containing the molten metal andby the fact that in said cores or in said metal male open feeding risersare provided for feeding the casting as the cooled metal shrinks and forattracting any slag, fumes and gases contained in the molten metal. 46.A mold according to claim 45, in which the upper part of the figure isobtained by cores, comprising a plate (45) destined to be pressed,during the casting phase, onto the upper surface of the mold to preventthe molten metal from overflowing through the risers.
 47. A moldaccording to claim 46, in which the plate is crossed by channels for thevacuuming of fumes and gases from the mold and is fastened to a support(46) in which there is a vacuum chamber (46″) communicating with anexternal vacuum device, said plate's vacuum channels being provided withfilters to prevent the passage of molten metal.
 48. A mold according toclaim 45, in which the upper part of the figure is obtained by the metalmale (51) and in which the male is fastened to a plate (45′) destined tobe pressed, during the casting phase, onto the upper surface of the moldto prevent the molten metal from overflowing through the risers.
 49. Amold for obtaining castings, especially engine cylinders heads, using alow-pressure casting procedure, where the upper part of the figure isdefined by a metal male (52), characterized by the fact that said metalmale is crossed by channels (52′) for the vacuuming of fumes and gasesfrom the mold and is fastened to a support (46) in which there is avacuum chamber (46″) communicating with an external vacuum device, saidmetal male's vacuum channels being provided with filters to prevent thepassage of molten metal.
 50. A mold according to claim 49, in which onlythe plate or the support with the vacuum chamber are jointed to thehydraulic cylinder (10) carried by the tilting arm (8) on a castingmachine for receiving a mold, where the mold is equipped with a bottomand an ejector plate extending downwards from said bottom, the castingmachine comprising a lower main structure (30) suitable for housing aholding or maintenance furnace (32) for feeding the mold in alow-pressure casting procedure, an upper main structure (31) resting onsaid lower structure, a base plate (29) resting on the upper mainstructure (31), a cooled plate (16) positioned on the base plate (19)and suitable for receiving the bottom (35) of the mold, and furthercomprising, underneath the cooled plate (16), a plate holder (17) to befastened to the ejectors plate of the mold and running verticallybetween an inactive lowered position and a raised casting expulsionposition.